In order to provide improved driving-, braking- and turning-performance of a pneumatic tire on icy or snowy road surfaces and wet road surfaces, there has been conventionally used a tread pattern as shown in FIG. 6. In this instance, triangular blocks and quadrangular blocks having substantially the same dimension are uniformly defined on the tread ground-contact surface, by main grooves and widthwise grooves. Moreover, sipes are generally provided in the defined blocks so as to improve the performance on icy or snowy road surfaces through a so-called edging effect.
When sipes are formed as described above for improving the edging effect, there is an instance wherein the blocks divided by the sipes undergo buckling upon contact with the ground. Thus, the triangular blocks and quadrangular blocks are generally designed to have a uniform, relatively large ground-contact area, to thereby provide an improved ground-contact property and secure performance on icy or snowy ground.
Attention is drawn to Patent Document 1: JP 2008-56057A.